A high-frequency treatment tool that treats body tissue, such as mucosae, by applying high-frequency current to the body tissue is known (for example, refer to PTL 1).
This high-frequency treatment tool has a structure in which a bar electrode unit is inserted into a through hole of an electrically insulating cap member provided at a distal end of a sheath such that the bar electrode unit can be advanced or retracted in the axis direction and a liquid, which has been sent through the sheath, can be released forward through a liquid feed opening of the cap member.
A radially spreading distal end portion is provided at a distal end of the bar electrode unit. Thus, by forming at least part of the liquid feed opening to be exposed on the outer side of the distal end portion in a front view of the cap member, the liquid to be released from the liquid feed opening is prevented from becoming blocked by the back side of the distal end portion of the bar electrode unit. According to the high-frequency treatment tool described in PTL 1, the liquid feed opening has a non-circular structure constituted by a small-diameter portion that is adjacent to and supports the bar electrode unit and a large diameter portion exposed on the outer side of the distal end portion.